Lithography technology has been one of the key enablers and drivers for the semiconductor industry for the past several decades. Lithography improvements have kept the cost for printing a silicon wafer roughly constant while exponentially reducing the transistor size, therefore dramatically increasing the number of transistors that can be printed per chip at a rate known as Moore's law. Integrated circuits (ICs) have been printed optically with improvements in lens and imaging material technology along with decreases in wavelength used, fueling the steady improvement of lithography technology. However, the end of optical lithography technology has been predicted by many and for many years.
Many technologies have been proposed and developed to improve on the performance of optical lithography. Some succeeded; but the cost and complexity grew rapidly. This has been true largely because it has been more economical to advance incremental improvements in the existing optical technology rather than displace it with a new one. What are needed are methods and apparatus for improving the performance of lithography without making the process non-economical or impracticable for production.